"Of course, that was long before the concept of permission-based email marketing – in fact, it was long before email marketing itself. People often tell me that I should have taken a patent on single opt-in in 1986 and another one on double opt-in in 1993, and I would be one of the richest guys in the world. Well, maybe – I guess I will never know. But one thing is for sure, if I were charging royalties for the use of double opt-in, there would be a lot more spam in our mailboxes."